My question is not what brand or model bolt cutter is the best. But rather, what do you look for if you want damned strong metal in the cutting jaws? Chrome steel? Vanadium steel? Induction hardened jaws, as opposed to surface hardened?

If you want bolt cutters that weren't going to get indigestion going through boron hardened steel, or stainless, but simply cold take all the force you cold put on them and come back to do it again...Like 11mm or 3/8 or thicker.

I just tried to cut 1/2" rebar with a pair of 36" bolt cutters on land, and it was a no go. It would be pretty hard to cut stout rigging on a bouncy boat, no mater what the jaws were made from.
An Angle Grinder with a cut off wheel is the bomb.

I second the angle grinder but would add that it be the portable version with rechargeable battery. As long as there isn't any flammable materials nearby for the sparks to light up I expect the grinder will cut anything a bolt cutter will and then some.

Take a look at the BlackHawk Super BoltMasters, they come in our breaching kits. Not cheap, but I can tell you from experience they have never failed to cut for me and some of these **** holes in the world have some amazingly tough pad locks.

[QUOTE=njoynthewater;2657923]I second the angle grinder but would add that it be the portable version with rechargeable battery. As long as there isn't any flammable materials nearby for the sparks to light up I expect the grinder will cut anything a bolt cutter will and then some.[/QUOTE Yes. A 4" grinder would be perfect Metabo rules, but there are other good ones out there. My Bosch is 15 years old and still going! That said, 1 mm 'wafer' (cut-off) wheels are VERY dangerous.
Unlike grinding wheels, which would work but be slower, wafer wheels routinely come apart, especially in inexperienced hands or awkward positions. I've been close to 2 people who lost an eye using these wheels, admittedly for lack of 'proper' Personal Protective Equipment (PPE) - although in one incident (in the weld test booth right next to me) the fragment of disc came right thru the plastic cover plate in his welding hood...and right over the top of his dime-store reading glasses. Like a knife through warm butter... Lots of sutures too over the years, including a dozen or so of my own. Of course in a life & death situation we do our best - I would certainly try to keep the 'line of fire' (sparks) well away from my face. And don't 'hog' (bear down) too hard on the disc! Let the grinder do it's work. It'll be just as fast.
Certainly in a practice situation, wear all the PPE you can find. Real safety glasses AND a face shield. I wear ANSI glasses and my hood with it's flip-up lens. Always.
Once that eye runs down your face, you're done. Once you heal up, it's time to start shopping for that dashing black eye patch!

Picking the steel alloy and the heat treating method is of interest to the manufacturer. The odds that they will share that information with you are slim. Also, there are many steels which can be hardened to a specific point and the choice of the alloy often has to do with other factors like cost, forgeability, the designers familiarity with the material, etc.

As A64 said, there is a tradeoff between hardness and brittleness.

In the real world, the most practical thing to do is to test them. By the way, the stainless steel commonly used on boats, 316 or 304, any 300 series alloy, is soft. It is not a challenge for any remotely good pair of cutters.

There are cutters made which are hydraulic powered. The cutting head is small and is connected to the pump with a hose. The hydraulics can give huge leverage. If you're looking for something manual, compact and powerful I'd give them a try.

And a 4 1/2" angle grinder with a 1/16" cut off wheel will easily go thru any steel or stainless item with little drama or stress. So long as it is calm enough to be dry on deck its an excellent choice.

I second the angle grinder but would add that it be the portable version with rechargeable battery. As long as there isn't any flammable materials nearby for the sparks to light up I expect the grinder will cut anything a bolt cutter will and then some.

Yup. First choice of bike thieves. A decent portable grinder will cut any lock that they can reach. Like less than 2 minutes for even the toughest commercial lock or chain.

I just tried to cut 1/2" rebar with a pair of 36" bolt cutters on land, and it was a no go. It would be pretty hard to cut stout rigging on a bouncy boat, no mater what the jaws were made from.
An Angle Grinder with a cut off wheel is the bomb.

belize-
Over the years every once in a while I have just met something that needed cutting, and decided it is time to add a good bolt cutter to the tool pile.

I have a corded angle grinder, didn't want to pick up a cordless one since that also means nursing batteries. I'm familiar with using grinders, and as a matter of fact have used a carbide hacksaw blade to do that same thing. It works, remarkably well, with a lot less noise and bulk.

Breaching kit: But of course! After all, a Halligan tool gets lonesome, all by itself.(G) And such a reasonable "departmental" price. (sigh)

For a couple of years there was an interesting emergency cutter for rod rigging on the market, which I didn't need and couldn't afford "just in case" at the time. Basically it clipped around a piece of rod, and then used a 12 gauge shotgun shell to fire a guillotine cutter blade through the rod. No batteries needed. Seems to have gone off the market though.

I'm looking for a bolt cutter, for heavy chain, odd bolts and bars, the occasional piece of steel that just really is being a nuisance. Including "Tell me you didn't just drop the keys overboard" padlocks, yes.

Beware of cheap bolt cutters. Bought one and the cutting surface dented on the first attempt at cutting off a lock. Essentially they wouldn't cut hardened steel and were throw aways after the attempt. Go with a tool from a reputable manufacturer and pay the price which will be substantial.

Have a Felco wire cutter that I've rerigged three boats with over the years, still going strong. Did have to add extension handles to get the leverage to cut 7mm and 10mm 7x19 wire. No way would I have the strength to cut the wire with the stock length handles.